1. Field of the Invention
The invention relates to operators for movable barriers, such as rolling shutters, gates and the like, and more particularly to operators which can be mounted on either side of an opening and which are automatically configurable for direction of opening and closing travel and end travel limits.
2. Description of Related Art
One of the problems which must be addressed in designing and engineering operators for movable barriers is the provision of automatic, safe and reliable stopping of the barrier at its open and closed positions. Most movable barrier operators include a head unit containing a motor and a transmission. The transmission may comprise a chain drive or a screw drive to be coupled to a barrier, such as a garage door, for opening and closing the garage door. As discussed in co-pending U.S. application Ser. No. 09/023,940, filed Feb. 13, 1998, which is incorporated herein by reference, such garage door openers also have included optical detection systems located near the bottom of the travel of the door to prevent the door from closing on objects or on persons that may be in the path of the door.
Such garage door operators typically include a wall control which is connected via one or more wires to an operator or head unit to send operation signals to the head unit from a remote location to cause the head unit to open and close the garage door, and to light a worklight. Such prior art garage door operators also include a receiver for receiving radio frequency transmissions from a hand-held code transmitter or from a keypad transmitter which may be affixed to the outside of the garage or other structure.
These garage door operators typically include adjustable limit switches which cause the garage door to reverse direction or which halt the motor when the travel of the door causes the limit switch to change state, either in the open position or in the closed position. In the prior art, internal limit switches have been provided within the head unit, and external limit switches have been provided at various locations outside of the head unit. It may be appreciated that the limits of travel typically must be custom set during or after installation of the unit within the garage. In the past, such units have had mechanically adjustable limit switches which are typically set by an installer. The installer may need to inspect the door, the wall switch and the head unit in order to make adjustments in order to set the limit switches properly. This, of course, is time consuming and results in the installer being required to spend more time than is desirable to install the garage door operator.
Requirements from Underwriters Laboratories, the Consumer Product Safety Commission, and/or other organizations require that garage door operators sold in the United States must, when operating in a closing mode and contacting an obstruction having a height of more than one inch, reverse and open the door. Prior art garage door operators also include systems whereby the force which the electric motor applied to the garage door through the transmission might be adjusted. Typically, this force is adjusted by a licensed repair technician or installer who obtains access to the inside of the head unit and adjusts a pair of potentiometers, one of which sets the maximum force to be applied during the closing portion of door operation, the other of which establishes the maximum force to be applied during the opening portion of door operation.
A garage door operator is exemplified by an operator taught in U.S. Pat. No. 4,638,443 to Schindler. However, such door operators are relatively inconvenient to install and invite misuse. If during operation the garage door operator begins to bind or jam in the tracks, the homeowner may obtain access to the head unit and increase the force limit. Increasing the maximum force may allow the door to move past a binding point, but also may undesirably apply increased force at the bottom of its travel.
Electrical limit switches are operated by physical contact between actuators and stops. However, the mechanical features of the switches and their electrical contacts are subject to strain, degradation caused by exposure to the surrounding environment, and other factors. As a results the limit switch set points may drift from their proper settings, and, under automatic operation, the door may not close or open as desired.
One particular problem can arise from drifting limit switch points when a homeowner, using a remote control unit, transmits a "close" command while driving away from a garage, but the garage door erroneously reverses automatically as it reaches the closed position. In this situation, the garage door may be left open for an extended time, unknown to the homeowner, permitting access to the garage and possibly an attached residence as well.
Drifting limit switch points frequently require the user or installer to readjust them. In order to readjust limit switch set points in prior art systems having internal limit switches, a user may be required to inspect the actuators from the vantage point of a ladder and, after determining the direction and amount of adjustment required, physically change their positions.
Commonly assigned U.S. patent application Ser. No. 09/023,940 discloses an improved control arrangement for garage door operators and the like which addresses several of the above problems. In particular, U.S. application Ser. No. 09/023,940 discloses a pass-point or position normalizing system consisting of a ring-like light interrupter attached to the garage door. As the door moves the interrupter crosses the light path of an optical obstacle detector signalling instantaneously the position of the door. The door continues until it closes, whereupon force sensing in the door causes an auto-reverse to take place which then raises the door to the up position. This completes the learn mode and sets the door travel limits. The pass-point system is also used to normalize the position of the position detector so that, over time, the end limits do not creep causing the door to crash into the floor or beyond the up limit. However, there is a continuing need for further improvement, particularly with respect to facilitating installation of a commercially practical apparatus addressing these problems.
Certain types of operators for commercial doors, gates and rolling shutters are designed be mounted on either side of the opening. For example, the operator for a rolling shutter can be mounted on the upper right hand side of a window or opening or the upper left hand side of the window or opening. The only difference in operation is the direction of rotation of the motor (or direction of travel) for opening and closing the shutters. For example, if the motor assembly is mounted on one side, the direction of rotation for opening is clockwise (CW); if mounted on the other side, the direction of rotation for opening is counter-clockwise (CCW).
An operator which has two possible installation configurations requires the installer to configure the unit at installation to travel in the correct direction. Such configuration may require setting switches or special programming, all of which is time consuming to the installer. Further, configuring the direction of travel impacts the location of the pass-point. The location of the pass-point is preferably set near the close position. Installing the operator in the opposite location would place the pass-point near the open position. Thus, there is a need for a movable barrier operator which automatically detects the direction of travel for open and close and always provides a pass-point in the preferred location.
The labor cost for installing a movable barrier operator is an important consideration both to installers and to users. Any step that can be automated translates into reduced costs. Programming the open and close limits in a movable barrier operator can sometimes take several steps. Many movable barrier operators are manually setable, such as by physically locating or adjusting the frame-mounted limit switches as described above. Other operators may require the user press the learn switch when the door is at a limit in the learn mode to program in the open and close limits. Not all users or installers may be able to accurately select the open and close limits by pressing the learn switch at just the right time or to select them on the first try. There is a need for a movable barrier operator which automatically learns the open and close barrier travel limits without actuation of a learn switch by the user.